Introduction
You're on a location scout and the director falls in love with a spot that gets direct sun for exactly 45 minutes before a building casts a shadow across it. You've got one window to shoot, and you need to dial in exposure fast. ISO up means more noise. Aperture open means shallower depth of field. Slower shutter means motion blur. Every adjustment pulls in two directions.
The exposure triangle simulator lets you experiment with ISO, shutter speed, and aperture interactively and see the downstream effects on brightness, depth of field, motion blur, and noise in real time. Instead of doing the mental math, you see the tradeoffs instantly.
This tool is built for the moments when three variables are fighting each other and you need to find the combination that serves the shot without sacrificing image quality.
What This Tool Calculates
The simulator accepts four inputs: a scene lighting condition (from bright daylight down to moonlight, expressed in lux), ISO sensitivity, aperture (f-stop), and shutter speed.
It calculates and displays six outputs. Exposure value (EV) quantifies the brightness of your current settings. Scene EV shows the brightness of your selected environment. The exposure offset in stops tells you how far over or under you are. Depth of field, motion blur, and noise indicators show the creative consequences of your current triangle balance.
The Formula and How It Works
Exposure value is calculated using the standard photographic formula: EV = log2(N squared / t), where N is the f-stop and t is the shutter speed in seconds. The ISO adjustment modifies this as: Camera EV = EV minus log2(ISO / 100).
Scene brightness in EV is derived from lux: Scene EV = log2(lux / 2.5). Bright daylight at 100,000 lux equals roughly EV 15.3. A well-lit interior at 500 lux equals EV 7.6. Moonlight at 0.25 lux equals approximately EV minus 3.3.
The exposure offset equals Scene EV minus Camera EV. A value of 0 means correct exposure. Positive values indicate overexposure. Negative values indicate underexposure.
Worked example: outdoors on an overcast day (20,000 lux, Scene EV = 12.97). Camera set to ISO 400, f/4, 1/125s. Camera EV = log2(16 / 0.008) minus log2(4) = 10.97 minus 2 = 8.97. Offset = 12.97 minus 8.97 = 4.0 stops overexposed. You need 4 stops of reduction: stop down to f/16, add a 4-stop ND, or increase shutter speed to 1/2000.
Real-World Examples
Balancing Shallow DoF with Bright Daylight
A DP shooting a wedding film at noon wanted a shallow depth of field look at f/1.4 on a Full Frame sensor. At ISO 100 and 1/4000s (the camera's fastest shutter), the simulator showed the scene was still 1.5 stops overexposed. The tool made it immediately clear that an ND filter was required. A 2-stop ND brought the exposure within range while preserving the wide-open bokeh.
Low-Light Concert Footage
A documentary crew shooting a jazz club performance at roughly 50 lux needed to find the balance between noise, motion blur, and depth of field. The simulator showed that ISO 3200, f/2.8, 1/48s produced correct exposure with moderate noise and natural motion blur. Pushing to ISO 6400 allowed f/4 for more DoF, but the noise indicator moved to "High." The crew chose ISO 3200 and managed noise in post with temporal denoising.
Matching Exposure Across Golden Hour
As golden hour progressed, a gaffer tracked the falling light from roughly 10,000 lux down to 2,000 lux over 40 minutes. The DP used the simulator to pre-plan the exposure ramp: start at ISO 400, f/5.6, 1/48s, then open to f/4 at 6,000 lux, then f/2.8 at 3,000 lux, then bump ISO to 800 at 2,000 lux. Each step maintained correct exposure with documented tradeoffs.
Scene Lighting Conditions and Typical EV Values
| Condition | Approx. Lux | Scene EV | Typical Settings |
|---|---|---|---|
| Bright Sunlight | 100,000 | 15.3 | ISO 100, f/11, 1/125 |
| Overcast Daylight | 20,000 | 13.0 | ISO 100, f/5.6, 1/125 |
| Golden Hour | 10,000 | 12.0 | ISO 200, f/4, 1/48 |
| Well-Lit Interior | 500 | 7.6 | ISO 800, f/2.8, 1/48 |
| Dim Interior | 50 | 4.3 | ISO 3200, f/2, 1/48 |
| Night Street | 10 | 2.0 | ISO 6400, f/1.4, 1/48 |
| Moonlight | 0.25 | -3.3 | ISO 12800, f/1.4, 1/8 |
Pro Tips and Common Mistakes
Pro Tips
- In cinema, shutter speed is usually fixed at 1/48s (180-degree shutter at 24fps). That removes one side of the triangle. Your real exposure variables are ISO and aperture, plus ND filtration when outdoors.
- When shooting in changing natural light, plan your exposure ramp in advance using the simulator. Know which parameter you'll adjust first so the transition is invisible to the viewer.
- Use the noise indicator as a guideline, not a hard limit. Modern cinema cameras like the Sony FX6 and ARRI ALEXA 35 produce usable images at ISO 3200 and above. Test your specific camera's noise floor before the shoot.
- The motion blur indicator changes meaning depending on your content. A 1/48s shutter is standard for narrative, but sports and action sequences often benefit from 1/96 or 1/120 for reduced blur.
Common Mistakes
- Adjusting all three parameters at once. Change one variable at a time and observe the effect. Opening aperture by 1 stop while also doubling ISO gives you 2 stops more light, not 1.
- Treating ISO as a free variable. Every ISO increase adds noise. On most cameras, the jump from ISO 800 to ISO 3200 is visually significant. Use aperture and ND adjustments first before pushing ISO.
- Forgetting that depth of field and motion blur are creative decisions, not just exposure tools. Opening to f/1.4 solves an exposure problem but may create a focus problem the 1st AC can't manage.
Frequently Asked Questions
What is the exposure triangle?
The exposure triangle describes the three camera settings that control image brightness: aperture (f-stop), shutter speed, and ISO. Each also has a creative side effect. Aperture controls depth of field. Shutter speed controls motion blur. ISO controls sensor noise.
How do I use the exposure triangle for video versus photography?
In video, shutter speed is typically locked to the 180-degree rule (1/48s at 24fps, 1/60s at 30fps). This eliminates one variable and reduces the triangle to aperture and ISO. Photographers have full freedom to adjust all three.
What EV value is correct exposure?
Correct exposure means your Camera EV matches the Scene EV, producing an offset of 0 stops. In practice, DPs often expose slightly under for a moodier look or slightly over for a bright, airy feel. A half-stop offset is a creative choice; two or more stops off is typically an error.
Can I use the simulator for HDR shooting?
Yes. HDR capture typically targets a middle exposure that preserves both highlights and shadows. Use the simulator to find settings that place your exposure offset at 0 or slightly negative. Most cinema cameras have 13 to 15 stops of dynamic range, so a half-stop offset still captures the full scene.
Start Calculating
The exposure triangle is the grammar of cinematography. Every shot is a sentence built from aperture, shutter, and ISO. Understanding how they interact makes you faster on set and more intentional in your choices.
Play with the sliders above until you find the balance for your next shoot. What's your default starting point for exposure, and which variable do you reach for first when conditions change?
